Studies on the molecular mechanism of the induction of SOS functions in Escherichia coli will be continued with a special emphasis on the role of specific deoxyoligonucleotides in the induction of prophage phi80. Attempts will be made to identify the intracellular target of the active deoxyoligonucleotides such as dGG, dAG and dIG, by employing highly labeled versions of these deoxydinucleotides. In parallel to the bacterial SOS system, we will initiate a series of experiments which aim to elucidate whether or not a similar system really exists in animal cells. Our plans include examination of the effect of various chemical and physical treatments of cultured animal cells on the production of latent viruses (for example,SV40), cellular differentiation and synthesis of specific proteins such as plasminogen activator. We will also test the effect of specific deoxyoligonucleotides, which are active in phi80 induction, on the various biological functions in animal cells as described above.